We propose a 2-arm, parallel group, randomized controlled trial to test the efficacy of adding innovative environmental strategies to reduce energy consumption to a standard family-based, group behavioral intervention for weight control in obese children. Since the 1960's, most behavioral interventions to change eating behavior for weight loss have primarily focused on self-control over food choices and amount of consumption. Recently, researchers have started to identify environmental factors that may influence intake without requiring conscious, cognitive self-control. A total of 160 8-15 year old obese children (BMI e 95th percentile) will be randomized to the two conditions. All children will participate with their parent(s)/guardian(s) in a standard six-month, weekly, family-based, group, behavioral weight control program. In addition, families randomized to the environmental strategies (ES) intervention condition will receive three environmental interventions that appear promising for purposes of weight control in obese children: (1) replacing short and wide and large volume glasses with tall and thin and small volume glasses, (2) replacing larger diameter and volume plates and bowls and utensils with smaller diameter and volume plates, bowls and utensils, and (3) eliminating eating while watching television and other screen media. Measures will be collected at baseline, 6 months (end of the behavioral treatment), and 18 months after baseline (one year after the end of the treatment program). Body Mass Index (BMI) is the primary outcome measure. The primary outcome analysis will compare individual trajectories of change in BMI in the treatment and control groups over the full 18-month follow-up, using random regression models. The study has e 80% power to detect a clinically-significant medium effect size (Cohen's d = 0.5) or greater difference between groups. Primary hypothesis: Children randomized to receive the environmental strategies intervention plus the standard family-based, group behavioral weight control program (the Treatment group), will significantly reduce their weight gain (BMI) over 18-months compared to children randomized to receive only the standard family-based, group behavioral weight control program (the Control group). Secondary hypotheses: Compared to Controls, children in the Treatment group will significantly reduce their BMI over 6-months and reduce their waist circumference, triceps skinfold thickness, systolic and diastolic blood pressures, resting heart rate, meals eaten with TV, daily dietary energy intake, fasting total cholesterol, LDL-cholesterol, triglycerides and insulin, weight concerns and depressive symptoms, and significantly increase their HDL-cholesterol self-esteem, and school performance, over 6- and 18-months. PUBLIC HEALTH RELEVANCE: Relevance: There is a need for effective weight control methods for obese children. Environmental strategies to reduce food consumption that do not require conscious, cognitive self- control are an innovative and promising approach. If effective, the clinical and public health implications would be great, providing a new paradigm to address the obesity epidemic.